diff --git a/src/pynwb/ndx_microscopy/testing/_mock.py b/src/pynwb/ndx_microscopy/testing/_mock.py
index ff8bb4d..98b7ad9 100644
--- a/src/pynwb/ndx_microscopy/testing/_mock.py
+++ b/src/pynwb/ndx_microscopy/testing/_mock.py
@@ -78,7 +78,7 @@ def mock_PlanarImagingSpace(
     name: Optional[str] = None,
     description: str = "This is a mock instance of a PlanarImagingSpace type to be used for rapid testing.",
     origin_coordinates: Tuple[float, float, float] = (-1.2, -0.6, -2),
-    grid_spacing_in_mm: Tuple[float, float, float] = (0.2, 0.2),
+    grid_spacing_in_um: Tuple[float, float, float] = (20, 20),
     location: str = "The location targeted by the mock imaging space.",
     reference_frame: str = "The reference frame of the mock planar imaging space.",
 ) -> ndx_microscopy.PlanarImagingSpace:
@@ -87,7 +87,7 @@ def mock_PlanarImagingSpace(
         description=description,
         microscope=microscope,
         origin_coordinates=origin_coordinates,
-        grid_spacing_in_mm=grid_spacing_in_mm,
+        grid_spacing_in_um=grid_spacing_in_um,
         location=location,
         reference_frame=reference_frame,
     )
@@ -100,7 +100,7 @@ def mock_VolumetricImagingSpace(
     name: Optional[str] = None,
     description: str = "This is a mock instance of a VolumetricImagingSpace type to be used for rapid testing.",
     origin_coordinates: Tuple[float, float, float] = (-1.2, -0.6, -2),
-    grid_spacing_in_mm: Tuple[float, float, float] = (0.2, 0.2, 0.5),
+    grid_spacing_in_um: Tuple[float, float, float] = (20, 20, 50),
     location: str = "The location targeted by the mock imaging space.",
     reference_frame: str = "The reference frame of the mock volumetric imaging space.",
 ) -> ndx_microscopy.VolumetricImagingSpace:
@@ -109,7 +109,7 @@ def mock_VolumetricImagingSpace(
         description=description,
         microscope=microscope,
         origin_coordinates=origin_coordinates,
-        grid_spacing_in_mm=grid_spacing_in_mm,
+        grid_spacing_in_um=grid_spacing_in_um,
         location=location,
         reference_frame=reference_frame,
     )